1. Field of the Invention
The present invention relates to a substrate edge treatment, and more particularly to a substrate edge treatment having a step of removing surface roughness of a substrate or a film that has adhered to the substrate.
2. Description of the Related Art
In a manufacturing process of a semiconductor device, an unnecessary part of a metal thin film formed at an end of a semiconductor wafer may be removed by etching in some cases. Various proposals have been conventionally made to suppress unintentional etching at the center of a wafer surface involved by scattering of an etchant in this process (see, e.g., Jpn. Pat. Appln. KOKAI Publication No. 2001-118824 or Jpn. Pat. Appln. KOKAI Publication No. 2002-299305).
Further, removal of a metal at a wafer end has been also a problem in a liquid immersion exposure tool that has recently come into practical use. The liquid immersion exposure tool corresponds to a technique that fills a space between a resist film surface and a lens of an exposure tool with a liquid to perform exposure when effecting exposure with respect to the resist film formed on a treatment target substrate. As a tool used for such an exposure technique, there is one disclosed in, e.g., Jpn. Pat. Appln. KOKAI Publication No. 303114-1998.
On the other hand, in liquid immersion exposure, an accuracy of a resist pattern cannot be possibly obtained because of, e.g., elution of a photosensitive agent or the like contained in a resist film into water, or penetration of water into the resist film. In order to avoid such problems, a water-repellent protection film is formed on the resist film. As the protection film, there are a developer soluble type protection film that can be solved in a developer and a solvent soluble type protection film that can be solved with a dedicated solvent. The protection film is removed after end of a series of coating/developing treatments.
In particular, in case of using the developer soluble type protection film, when a developer is supplied to an upper side of a water-repellent protection film in a developing treatment after liquid immersion exposure, since the developer is repelled on a surface of the protection film from a substrate edge, the protection film cannot be sufficiently solved at the substrate edge and it may possibly remains as a residue even after end of the developing treatment. When etching step or the like is carried out in this state, the protection film remaining at the substrate edge serves as a mask, and sharp-pointed protrusions are generated at the substrate edge. These protrusions become particles to disadvantageously contaminate a carriage portion and others in an etching device.
As explained above, in a state where the sharp-pointed protrusions remain at the substrate edge or a bevel of this part, when a resist film is coated/exposed/developed at a subsequent lithography step to form a resist pattern, an organic film enters a groove between the protrusions, and this film may not be possibly removed even after end of development. Further, when an etching step or the like is carried out in this state, the organic film remaining at the substrate edge become particles to disadvantageously contaminate a carriage portion or the like in an etching device.
Therefore, realization of a substrate treatment that can remove a resist pattern even after end of development and avoid occurrence of particles even in a state where sharp-pointed protrusions remain at a substrate edge or a substrate bevel has been demanded.